A researcher knew that before cell phones, a person made on average 2.8 phone calls per day. She believes that the number of phone calls made per day today is higher. A random sample of 30 people had a sample mean x = 3.1. The standard deviation for the population found by a previous study is o = 0.8. Test the hypothesis that the population mean is 2.8 against the .. alternative hypothesis that the population mean is greater than 2.8,at the 0.05 level of significance.

Q: Experience has shown that the value of orders placed by customers of Handy Glass Pty is normally…

A: From the provided information, Mean (µ) = 200 Standard deviation (σ) = 755 Sample size (n) = 85

Q: Assuming that the scores of Grade 11 students in Statistics and Probability in their third quarter…

A:

Q: For a population: a. with a standard deviation of σ= 15, how large a sample would be needed to…

A: Given a) For population standard deviation of  σ= 15, standard error of 7    b) For population…

Q: population with a standard deviation of 20, how large a sample is necessary to have a standard error

A: Given that  Population with standard deviation (σ) = 20   We know that  Standard error (SE) = σn…

Q: From a normally distributed population, we took a simple random sample of 700 students with a mean…

A:

Q: A z-score of −1 tells us that a score fell one standard deviation below the mean in a group of…

A: Empirical rule: For a normal distribution, the approximate values that fall in the specified…

Q: In a population with a mean of µ = 30 and a standard deviation of σ = 5, a score of X = 18 would be…

A: Given that  μ=30 , σ=5 , X=18

Q: A manufacturer is interested in the output voltage of a power supply used in a PC. Output voltage is…

A:

Q: A sample of n = 5 scores has ΣX = 20 and ΣX2 = 180. For this sample, what is the value of the sample…

A: According to the provided information,   n = 5  ΣX = 20 ΣX2 = 180

Q: A firm specializing in the preparation of income tax returns, claims the mean refund for customers…

A: State the hypotheses.

Q: A researcher finds that the mean income (in dollars per week) of a sample of people who live in a…

A: Given:

Q: A large retailer wants to determine whether the mean income of families living within two miles of a…

A: Denote μ as the population mean income of families living within two miles of proposed building…

Q: An orange juice producer buys all his oranges from a large orange grove. The amount of juice…

A: Given: μ=4.7 and σ=0.4. d)From the given…

Q: Suppose a company produces lightbulbs with a mean lifetime of 1000 hours and a standard deviation of…

A: Given that, Mean= 1000 And standard deviation, sigma= 50 We know that, Z Score= (X-mu)/sigma

Q: A small pilot study was conducted to compare cholesterol levels in individuals before and after a…

A: Preliminary calculation:Using the EXCEL formula “=NORM.S.INV(1– (0.05/2))”, the z-value for 95%…

Q: )A potato chip manufacturer has found that in the past the standard deviation of bag weight has been…

A:

Q: A sample of n=25 scores has a mean of 68. Find the z-score for this sample. If it was obtained from…

A:

Q: A previous study claims that the average time a teenager spends browsing his social media accounts…

A: Sample size(n)=100 Population mean(μ)=6 Sample mean(x)=5.5 Standard deviation(σ)=0.5

Q: A medical statistician wants to estimate the average weight loss of people who are on a new diet…

A:

Q: For a large metropolitan area, carbon monoxide concentrations in air samples come from a normal…

A: We have to find out answer of given question....

Q: A random sample of 75 eighth grade students scores on a national mathematics assessment  test has a…

A: Population mean (µ) = 270Standard deviations (σ) = 30Sample size (n) = 75Sample mean (x̅) =…

Q: A fast food restaurant sells hamburgers and chicken sandwiches. On a typical weekday the demand for…

A: The normal distribution:A continuous random variable X is said to follow normal distribution with…

Q: Suppose you were to take samples of size 100 from a population with a mean of 12 and a standard…

A: The formula of the standard error of the mean is,

Q: A sample of n = 5 scores has Σ X = 20 and Σ X2 = 180. For this sample, what is the value of the…

A:

Q: A previous study claims that the average time a teenager spends browsing his social media accounts…

A:

Q: A graduate student is performing a study on a new anti-anxiety drug. The drug is supposed to reduce…

A: Consider that μanti-anxiety drug is the mean for the population of anxious people, who take the…

Q: For a population with  = 150, a raw score of X = 125 corresponds to z = -2.00.  What is the standard…

A: Consider that the mean and standard deviation of a random variable x are µ and σ, respectively.…

Q: For a normally distributed population with a mean of 35 and a standard deviation of 7.5, what value…

A: X follows a Normal distribution with mean = 35 and S.D = 7.5 Then z=(x-mean)/SD = (x-35)/7.5…

Q: A random sample of size 25 from a popúlation gives the sample standard deviation to be 8.5. Test the…

A:

Q: An insurance agent says the standard deviation of the total hospital charges for patients involved…

A:

Q: For a normally distributed population with a mean of 35 and a standard deviation of 7.5, what value…

A: From the given information, normal distribution with population mean as 35 and standard deviation as…

Q: Suppose that for the past several decades, daily precipitation in Seattle, Washington has had a mean…

A: Power of the test is the probability of rejecting null hypothesis when the null hypothesis is false.…

Q: The results of a national survey showed that on average, adults sleep 6.9 hours per night.Suppose…

A:

Q: Given a sample with a mean of 78 and a standard deviation of 14, find x such that Pr(X < x) = 0.70.…

A: We have to find x such that Pr(X &lt; x) = 0.70

Q: 32 individuals from a population and the mean of the population is 120 and the standard deviation of…

A: From the central limit theorem the sample mean blood glucose level will follow normal distribution…

Q: Assuming you obtained a random sample of blood glucose levels from 32 individuals from a population…

A: It is given that the mean is 120 and the standard deviation is 15.

Q: A sample of n = 25 scores has a mean of M = 40 and a standard deviation of s = 10. What is the…

A: Mean = 40 Standard deviation = 10 Sample size , n = 25

Q: A recent study found that 61 children who watched a commercial for potato chips featuring a…

A: Denote μ1, μ2 as the population mean weights of potato chips eaten by children who watched the​…

Q: A recent study showed that the average number of sticks of gum a person chews in a week is 10. A…

A: The correct hypothesis would be: H0:μ≤10HA:μ&gt;10(claim)

Q: The heights of river birch trees are normally distributed with a mean of 92.3 inches and a standard…

A: Given that the heights of a river birch trees are normally distributed with  mean of 92.3 inches and…

Q: A medical statistician wants to estimate the average weight loss of people who are on a new diet…

A: Solution: Given information: σ= 10  Population standard deviation E= 2 Margin of error C= 0.9=90%…

Q: A firm specializing in the preparation of income tax returns, claims the mean refund for customers…

A: State the hypotheses.

Q: The results of a national survey showed that on average, adults sleep 6.9 hours per night.Suppose…

A: (a) The mean of the samples hours that adults sleep is 6.9 hours and standard deviation is 1.2…

Q: A technical training firm claims that the average time for their trainees to master a particular…

A: Given: The number of students tested every month is n=24. The sample mean time for their trainees to…

Q: A researcher wishes to see if the average number of sick days a worker takes per year is greater…

A: From provided information, claim that the average number of sick days a worker takes per year is…

Q: A math teacher claims that the mean scores on a math assessment test for fourth grade boys and girls…

A: The provided information is  x¯2=151x¯2=149s1=36s2=34n1=13n2=15α=0.01 a.The null and alternative…

Q: A researcher wishes to see if the average number of sick days a worker takes per year is greater…

A: Hypotheses:Let µ be the true average number of sick days a worker takes per year. The aim of the…

Q: Q2) A certain machine makes electrical resistors having a mean resistance of 60 ohms and a standard…

A: Given information: μ=60, σ=2

Confidence Intervals

When we calculate intervals in probability and statistics, it can be simply termed as finding out a confidence interval. The confidence interval is usually calculated from the data set which is observed. The value of the parameter that needs to be calculated is present here only.